1. Field of the Invention
The present invention generally relates to the mounting of electric component parts successively on a printed circuit board by the utilization of a suction force for picking up electric component parts.
2. Description of the Prior Art
In order for an electric component to be mounted on a printed circuit board so accurately and so correctly as to allow the electric component to assume a predetermined position on the printed circuit board, the conventional practice makes use of a vision sensing system including video cameras for recognizing the position of the printed circuit board at which the electric component is to be actually mounted and also for recognizing the position of the electric component retained by the mounting head. When the component mounting apparatus is in operation, the system is cyclically sequenced to cause the video camera in the mounting head to recognize the position on the printed circuit board at which an electric component is to be mounted; then to cause the mounting head to be moved to a component supply station to pick up the electric component; to cause the video camera, fixed installed at a predetermined position on the path of travel of the electric component from the component supply station towards the component mounting station, to recognize the position of the electric component being transported towards the mounting station; to cause the electric component to be actually mounted so as to assume the predetermined position on the printed circuit board which has been recognized by the video camera; and finally to cause the video camera in the mounting head to recognize the position on the printed circuit board at which the next suceeding electric component is to be mounted.
According to the above discussed prior art component mounting method, the recognition of the electric component having been retained by the suction nozzle and the recognition of the mounting position on the printed circuit board are performed separately. Accordingly, not only is a relatively long time required to finish the task of recognition, but also a limitation is encountered in reducing the tact time incurred during the component mounting operation and also in improving the mounting accuracy. Considering the recent trend that the spacing between each neighboring lead lines extending outwardly from an electric component is reduced with an increase in number of the lead lines, demands have been made recently for achieving a highly accurate mounting of electric components and, therefore, the problems inherent in the prior art component mounting method can no longer be negligible.
Also, in order to avoid any possible spoilage of one or both of the electric component and the printed circuit board only because of a failure of the electric component to be properly mounted and/or a failure of the printed circuit board to receive the electric component, inspection is required to determine if the electric component has been properly mounted. According to the prior art component mounting method, not only is this inspection carried out separtely from the component mounting operation, but also the adjustment or repositioning of the electric component mounted incorrectly is performed manually, the productivity is relatively low.